As such a microwave generating apparatus, mainly used as a heating apparatus, an apparatus in which a coil is formed around the magnet portion of a magnetron for consumer use, and control of the frequency/phase of a microwave oscillated from the magnetron, is realized by combining control of a magnetic field strength and injection locking (e.g. refer to a patent document 1), and an apparatus in which control of the frequency/phase of a microwave oscillated from the magnetron, is realized by combining phase-locked loop (PLL) with respect to the power supply of the magnetron for commercial use and injection locking (e.g. refer to a patent document 2) are proposed.
Patent document 1: Japanese Patent Application Laying Open NO. Sho 60-123110
Patent document 2: Japanese Patent Application Laying Open NO. 2002-43848
However, in the conventional microwave generating apparatus, as described in the patent documents 1 and 2, a desired characteristic can be obtained with regard to the control of the frequency/amplitude of the microwave; however, it is difficult to control the amplitude of the microwave. Thus, this apparatus is applied only to a heating apparatus. Therefore, in the present circumstances, the conventional microwave generating apparatus cannot be applied to a plasma generating apparatus, a communicating apparatus, a radar apparatus, or the like, in which it is necessary to stabilize or control the amplitude of the microwave of the magnetron, simultaneously with the stabilization or control of the frequency/phase of the microwave of the magnetron.